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UNITED STATES PATENT OFFICE.

WILLIAM E. HATHAWAY AND WILL B. JOHNSTON, OF HORNELLSVILLE,

NEW YORK.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 265,412, dated October3, 1882,

Application filed June 8, 1882. (No model.)

To all whom it may concern:

Be it known that we, TILLIAM E. HATHA- WAY and WILL B. J OIINSTON,citizens of the United States, residing at Hornellsville, in the countyof Steuben and State of New York, have invented new and usefulImprovements in Mechanical Telephones, of which the following is aspecification.

Our invention relates to mechanical telephones; and it consists informing the dia phragm or vibrating plate of isinglass or of mica, andin supporting the same by anetted or textile fabric which extends overthe entire surface of said diaphragm and affords means of attachment tothe base of the casing.

Referring to the drawings, Figure 1 is a vertical section taken throughthe center of the casing. Fig. 2 is a front elevation of the basepiece,the mouth-piece being'removed and a portion of the diaphragm beingbroken away to show the supporting fabric. Fig. 3 is a view of thediaphragm with its supporting fabric detached from the casing.

The letter A in said drawings indicates the mouth-piece, and B thebase-piece, both being made of wood in the usual form and united bymeans of screws to a.

U indicates the diaphragm, which is formed of isinglass or mica; andDindicates any suitable netted or textile fabric lying behind thediaphragm O and in close contact therewith.

E indicates the linewire, which passes through a central perforation inthe diaphragm, and is fastened to a button, F, which is drawn againstthe face of the said diaphragm by the tension of the wire E.

The netted or textile fabric supporting the diaphragm may be either finewire-gauze, silk, canvas, or any other suitable material. As a generalrule, however, we prefer silk or an equivalent textile fabric, becauseof its superior strength. The fabric used, whether the same bewire-gauze, as shown in Fig. 3, or silk, as shown in Fig. 2, should becut into circular shape of proper size, and, together with thediaphragm, isattached to the base-piece B by being laid in an annularrecess, with a leather strip or ring, I), placed upon it, and havingnails driven through the said ring,diaphragm,

and netted fabric, and into the wood of the base 13. Before beingattached in this manner the silk or other fabric should be tightlystretched upon the diaphragm in order to insure as perfect a contact andsupports as possible.

It is evident that instead of nailing these parts to the base they maybe cemented or glued thereto.

By employing mica or isinglass as a material for the vibrating plate ordiaphragm we obtain a much betterinstrument,the substance named beingfar more resonant than any other heretofore used in this class ofapparatus.

By re-enforcing the isinglass in the manner described the necessarytension may be applied to the wire, the silk, wire-netting, or otherfabric giving the required resistance and preventing the mica of thediaphragm from receiving any injury therefrom.

The diaphragm may be made of mica or of isinglass withoutthe supportingfabric by using a double plate.

WVhat we claim is 1. In mechanical telephones, a diaphragm or vibratingplate formed of isinglass or mica, and having a netted fabric stretchedbehind and adapted to support said diaphragm, substantially asdescribed.

2. In combination with the diaphragm C, a netted or textile fabric, D,stretched behind and in contact with said diaphragm, when the latter isattached to the box, substantially as described.

In testimony whereof we have hereunto set our hands in the presence oftwo subscribing witnesses.

IVILLIAM E. IIATHAWAY. \VILL B. JOHNSTON.

Witnesses:

FAY I RATHBUN, HARRISON NILEs.

